In general, roll blinds are installed on windows of various buildings to block external light, adjust indoor lighting, or avoid exposure of indoor privacy.
Such a roll blind typically has a single piece of blind material or a plurality of slats, which are installed in the horizontal direction, and which are rolled up around the overlying winding rod to be stored, or rolled down from the winding rod to cover the window.
FIG. 1 shows an exemplary conventional roll blind 1.
The conventional roll blind 1 includes a frame 10 attached to a wall, etc.; driving and driven brackets 12 and 14 installed on both sides of the frame 10, respectively; a winding rod 20 rotatably mounted between the brackets 12 and 14 in the form of a pipe; a blind material 30 wound around the winding rod 20; and a weight 40 fixed to the bottom of the blind material 30 to roll down and unwind the blind material 30 from the winding rod 20 by its own weight.
The driving bracket 12 contains a chain pulley 50 integrally connected to the winding rod 20 and rotated accordingly. A pulling cord 60 is wound around the chain pulley 50 so that pulling of one side of the pulling cord 60 rotates, through the chain pulley 50, the winding rod 20, which then winds up the blind material 30.
On the other hand, pulling of the other side of the pulling cord 60 rotates the chain pulley 50 and thus the winding rod 20 in the opposite direction so that the blind material 30 is unwound from the winding rod 20 and lowered.
The pulling cord 60, which is operated by the user to roll up or down the blind material 30, is a type of continuous track that is wound around the chain pulley 50. The lower end of the pulling cord 60, as shown in FIG. 1, hangs down a considerable length and may cause a very dangerous situation.
For example, a child may hide behind the blind material 30, which hangs down, during hide-and-seek, and the continuous track-type pulling cord 60 may be accidently wound around the child's neck.
In such a case, the pulling cord 60 could turn very fatal when wound around a child's neck, and there has even been reports that, if a child falls over with such a pulling cord 60 wound around the neck, he/she may be easily choked.
Such a conventional continuous track-type pulling cord 60 of a roll blind 1 is dangerous not only to children, as mentioned above, but also to elderly people, who may stumble on the cord and fall over.
It is necessary, in order to solve the above-mentioned problems, that the pulling cord 60 be not continuous, as in the case of the conventional continuous track type, and the pulling cord 60 be positioned high enough to prevent children from reaching it or elderly people from stumbling on it.
However, conventional technology has a limitation in that, if the lower end of the pulling cord 60 of a roll blind 1 is separated to reduce its length, and if it is positioned high enough to prevent children from reaching it, it becomes impossible to raise/lower the blind material 30 as desired. This necessitates new technology to tackle this issue.
Furthermore, some conventional roll blinds generate unpleasant noise (e.g. tinkling or rattling) when the clutch is operated to raise/lower the blind material 30, which compromises the quietness of indoor environment. This is another problem to be solved.